Add support for the Authenticated Registries

[anujc25]

What this PR does / why we need it

• Add support for the Authenticated Registry
• To use registries that require authentication to host Tanzu CLI Plugins images users are expected to do the following:

1. Use docker login <registry> or crane auth login <registry> to authenticate with the registry
2. Specify environment variable TANZU_CLI_AUTHENTICATED_REGISTRY=<registry>. By specifying this environment variable, Tanzu CLI will use the default authentication mechanism instead of using Anonymous access to fetch images.

Pending

• Add E2E tests

Which issue(s) this PR fixes

Fixes #

Describe testing done for PR

• Start local authenticated registry for testing

  
  # Start local registry at `localhost:5001`
  $ make start-test-central-repo

Start local registry requiring authentication at localhost:6002

$ make start-airgapped-local-registry

* Setup local authenticated registry with plugins

$ tz plugin download-bundle --to-tar /tmp/plugins.tar.gz --image localhost:9876/tanzu-cli/plugins/airgapped:small ... [i] saving plugin bundle at: /tmp/plugins.tar.gz

---

$ tz plugin upload-bundle --tar /tmp/plugins.tar.gz --to-repo localhost:6002/test/plugins [i] extracting "/tmp/plugins.tar.gz" for processing... [i] --------------------------- [i] uploading image "localhost:6002/test/plugins/airgapped" [i] copy | importing 2 images...

[i] copy | copy | done uploading images [i] copy | Error: Error uploading images: HEAD http://localhost:6002/v2/test/plugins/airgapped/manifests/sha256-b3e204740c44151562050f9f5b839386231c135a7cde944f150bca0503cbeb8f.imgpkg: unexpected status code 401 Unauthorized (HEAD responses have no body, use GET for details) [x] : error while uploading image: HEAD http://localhost:6002/v2/test/plugins/airgapped/manifests/sha256-b3e204740c44151562050f9f5b839386231c135a7cde944f150bca0503cbeb8f.imgpkg: unexpected status code 401 Unauthorized (HEAD responses have no body, use GET for details)

---

$ docker login localhost:6002 Username: testuser Password: Login Succeeded

---

$ tz plugin upload-bundle --tar /tmp/plugins.tar.gz --to-repo localhost:6002/test/plugins ... [i] successfully published all plugin images to "localhost:6002/test/plugins/airgapped:small"

---

$ docker logout localhost:6002 Removing login credentials for localhost:6002

* Now, Try to use the authenticated registry `localhost:6002` as discovery source

export TANZU_CLI_PLUGIN_DISCOVERY_IMAGE_SIGNATURE_VERIFICATION_SKIP_LIST=localhost:6002/test/plugins/airgapped:small export TANZU_CLI_AUTHENTICATED_REGISTRY=localhost:6002/test/plugins/airgapped:small

$ tz plugin source update default -u localhost:6002/test/plugins/airgapped:small [i] Refreshing plugin inventory cache for "localhost:6002/test/plugins/airgapped:small", this will take a few seconds. [x] : unable to fetch the inventory of discovery 'default' for plugins: plugins discovery image resolution failed. Please check that the repository image URL "localhost:6002/test/plugins/airgapped:small" is correct: error getting the image digest: GET http://localhost:6002/v2/test/plugins/airgapped/manifests/small: UNAUTHORIZED: authentication required; [map[Action:pull Class: Name:test/plugins/airgapped Type:repository]]

* Authenticate with the registry with (`docker login` or `crane auth login`) and try again

$ docker login localhost:6002 Username: testuser Password: Login Succeeded

---

$ tz plugin source update default -u localhost:6002/test/plugins/airgapped:small [i] Refreshing plugin inventory cache for "localhost:6002/test/plugins/airgapped:small", this will take a few seconds. [i] Reading plugin inventory for "localhost:6002/test/plugins/airgapped:small", this will take a few seconds. [!] Skipping the plugins discovery image signature verification for "localhost:6002/test/plugins/airgapped:small"

[ok] updated discovery source default

---

$ tz plugin search [i] The tanzu cli essential plugins are outdated and are being updated now. The update may take a few seconds. [i] Installing plugins from plugin group 'vmware-tanzucli/essentials:v9.9.9' [i] Installed plugin 'telemetry:v9.9.9' with target 'global'

NAME DESCRIPTION TARGET LATEST account account functionality mission-control v9.9.9 cluster cluster functionality kubernetes v9.9.9 clustergroup clustergroup functionality operations v9.9.9 isolated-cluster isolated-cluster functionality global v9.9.9 plugin-with-sha plugin-with-sha functionality global v9.9.9 telemetry telemetry functionality global v9.9.9

---

$ tz plugin install account [i] Installed plugin 'account:v9.9.9' with target 'mission-control' [ok] successfully installed 'account' plugin

<!-- Example: Created vSphere workload cluster to verify change. -->

### Release note
<!--
     Please add a short text (limit to 1 to 2 sentences if possible) in the release-note block below if
     there is anything in this PR that is worthy of mention in the next release.

     See https://github.com/vmware-tanzu/tanzu-cli/blob/main/docs/release/release-notes.md#does-my-pull-request-need-a-release-note
     for more details.
-->
```release-note
Add support for the Authenticated Registry to host Tanzu CLI plugin images

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